Went to start the Corvair for the first time in a couple of weeks... Fired right up, however the gas gauge was reading empty. When I filled the tank, it only took about 3 gallons, of which about 1 gallon hit the pavement.

Leak is not coming from the sender unit... Looks like from the top of the tank? Also, sender unit was replace last year, and has worked fine since. Can the leak also impact the sender's ability to function? Thanks!

Most likely the hose has been rotted for a while but only leaks when filled all the way. I have had that happen twice to my cars. Had one for a month b4 I filled it for the first time and lost about a gallon cuz the hose was rotten

Quick check to see if the gauge is working correctly is to remove the wire from the sender then turn on the key and observe the gauge, then ground the sending wire to the chassis and observe the gauge. I don't recall which way is which right now but it should be obvious if the gauge is working. One way should send the gauge to full and the other will show empty. There's really no way to check the sender until it's out of the tank.

..ground wire from the sender to the rusty panel needs to be replaced,,I run a new,longer wire inside,along the wiring harness up the toe-board cover..disconnect the tan sender wire,,gauge will go 'full' with Ign key ON, 'empty' when it's grounded..bad DASH cluster ground will not let the gauge move at all (IIRC..)

All 1960-1969 Corvair fuel gauges work the same way. There are two major parts to the fuel gauge system. There's the gauge with the needle you see in the dashboard and there's a float with a sender inside the fuel tank. The gauge and the sender are connected by electrical wiring.

Anybody can see what the gas gauge in the dashboard does, but what about the float and sender inside the fuel tank? The float rides up and down inside the tank depending on how much gasoline is in there. The float is connected to the sender which allows a weak electrical current to pass through the gauge when the tank is full and a strong electrical current to pass through the gauge when the tank is empty. The sender is what's known as a variable resistor. In 60-64 cars the sender resistance is 0 to 30 ohms. In 65-69 cars the sender resistance is 0 to 90 ohms.

The fuel gauge needle is mounted between two magnetic coils. One coil is on the "F" side of the gauge and the other is on the "E" side of the gauge. Both coils are wired to the ignition circuit and receive battery voltage whenever the ignition switch is on.

The magnetic coil that pulls the needle toward F (Let's call this the F coil) is grounded at the instrument panel and applies a constant magnetic force to the needle. The magnetic coil that pulls the needle toward E (Let's call this the E coil) has more windings for greater magnetic strength and is grounded through the variable resistor in the sender attached to the fuel tank float.

When the fuel tank is full the resistance in the sender is high (30 or 90 ohms) which reduces electrical current and magnetic strength in the fuel gauge E coil allowing the F coil to pull the gauge needle to F.

When the fuel tank is nearly empty and the float is near the bottom of the tank the resistance in the sender is at 0 ohms. The fuel gauge E coil receives full current, has enough magnetic strength to overcome the strength of the F coil and pulls the gauge needle to E.

When the ignition switch is turned off both fuel gauge coils lose power, magnetic force drops, and the needle remains where it is.

If there is a break in the tank sender wiring or a failure of the tank sender that creates an open circuit, the fuel gauge F coil will not be balanced by any magnetic force from the E coil and the needle will be pulled to the right beyond the F mark on the gauge when the ignition switch is on.

If there is a break in the wiring to the F coil or a poor electrical ground on the dash, the needle will be pulled to the left beyond the E mark on the gauge when the ignition switch is on, or the needle may move erratically when the dash lights, turn indicators, or other electrical systems are operated.

Credit for most of the information here goes to Dale Dewald who is a regular contributor to the Virtual Vairs internet email list.

Resurrecting an old thread....I have the same problem, and I live in Fort Collins, CO also (But I see the OP has not posted anything in over a year).

Sooo...new to me '64 MSC. Filling up with gas for the first time (gauge says empty). Next thing I know gas is poaring out inboard of the driver's side front wheel.

So the garage (and hence the house) reeks of gas now. Wife is not happy.

Tonight I am going to cut the fuel line and drain the tank to hopefully reduce the gas smell. Then I'll be removing the tank to inspect it and the area and go from there!

Any tips on tank removal on an EM? My guess is the filler flex/rubber hose will just separate as the tank comes down. My big question is can you drop the turbo fuel return line with the tank, then disconnect it? It appears that it's way up there with very little space to get in there. How high do I have to get the car? I have 12 ton jackstands as well as stacks of 2x12's that I can space them up higher with.

So I got the car up on jackstands tonight and drained the gas tank. It was nearly full!! I pulled about 12-13 gallons of fuel from it.

Soooo...my gas gauge doesn't work. It's pegged at about empty. I checked the ground on the sender and it's good. Sender and gas tank look like they were replaced by the PO. Tank is black with no rust and only a few scratches. Sender looks new(er) and shiny.

Interesting finding...the flex hose that I thought was disintegrating looks OK, but it appears the PO (or the PO's mechanic) replaced it with some universal hose (not specific/correct hose) as there are three (yes three!!) hose clamps wrapped around the top of the hose on top of each other, apparently trying to get it to seal. So when the tank was filled nearly full gas poared out of the poor upper seal on the generic flex hose.

I will drop the tank this weekend and take inventory of parts to replace including the correct hose(s).

What should I check next on the gas gauge to make sure it's a bad sender?

I too will guess whoever replaced the filler neck hose couldn't find the correct diameter wherever they were. They used oversize and thus the extra clamps.

As an aside, there is a club here in Denver and numerous members live in Ft. Collins/Loveland/Longmont. You need to be a part of it, possibly someone up there has a float and the hose. I have hose at my shop but not sure about a float.